Brain imaging study reveals why some teens use drugs and others don't

Newly discovered networks in the adolescent brain explain why some teens are more likely to say yes to experimentation with alcohol, cigarettes and illegal drugs.

When I met with teen brain researcher Dr. Abigail Baird I first asked her, "Why is it that teens are such a mystery to most adults?" We've all been teens ourselves, why are they so hard for us to relate to?

"I think just the heterogeneity of of what can happen in adolescence makes people very nervous," she explained, "and it's made it very hard to study because we could bring five thirteen-year-old's into the room and they could be at five completely different points of development."

A team of scientists at the University of Vermont, along with a large group of international researchers, set out to find the brain wiring behind those individual differences.

By studying 1,896 14-year-olds, they pinpointed unique brain networks that deal with impulse management, and found that activity levels in these networks correspond to teens' liklihood to experiment with alcohol, cigarettes and illegal drugs. Their findings came out this weekend in the journal Nature Neuroscience.

Using functional magnetic resonance imaging (fMRI), they found seven networks involved when impulses were successfully inhibited and six networks involved when impulse inhibition failed. A University of Vermont press release explains:

These networks "light up," in a functional MRI scanner during trials when the teenagers were asked to perform a repetitive task that involved pushing a button on a keyboard, but then were able to successfully stop—or inhibit—the act of pushing the button in mid-action. Those teens with better inhibitory control were able to succeed at this task faster.

A network "lighting up" in an fMRI scan suggests increased blood flow in that area, meaning greater activity there. Teens with greater activity in their orbitofrontal cortex (a region in the front of the brain's frontal lobes that's involved in decision making) performed better at inhibiting their impulses.

The researchers found that one particular network in the orbitofrontal cortex specifically correlated with an early adolescent's likelihood of starting to use drugs. The study reports that illegal drug use was also "associated with genetic variation in a norepinephrine transporter gene."

The press release states:

This discovery helps answer a long-standing chicken-or-egg question about whether certain brain patterns come before drug use—or are caused by it.

The take home message? A teen's susceptibility to impulsive behavior may be seen in both her brain activity and her genes. Being able to identify which teens are at greater risk for making dicey choices could allow physicians or counselors to intercede before dicey behavior starts.

It will be interesting to see clinical applications of this knowledge, as I don't foresee mandatory brain screenings for impulse susceptibility becoming de rigueur any time soon.

Photo: Incase/Flickr

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